This invention relates to a trim angle control device for marine propulsion motors and more particularly to an improved arrangement for controlling the trim position of a marine outboard drive and which is responsive to watercraft speed.
It is well known to support a marine outboard drive (either an outboard motor or the outboard drive portion of an inboard/outboard unit) for pivotal movement about a horizontally extending tilt axis. This pivotal movement is employed for permitting the outboard drive to be tilted up out of the water when not in use or, alternatively, for adjustment of the trim position of the outboard drive during operation of the associated watercraft. It is also well known that the optimum trim angle of the outboard drive varies with the running condition of the watercraft. A wide variety of power units are employed for effecting the pivotal movement of the outboard drive to adjust its trim position during running. Many of these devices are purely manual and require the operator's attention to set the trim angle for the various running conditions. Other devices, which are completely automatic, have also been proposed. The manual devices have the disadvantage of requiring the operator's attention so as to set the trim angle and thus divert from his other duties. Automatic systems, on the other hand, tend to cause frequent hunting of the position of the outboard drive and will adjust its position to compensate for transitory conditions. As a result, these devices do not actually provide the optimum trim angle under all conditions, particularly during transition from one condition to another.
In the copending application entitled "Trim Angle Control Device For Marine Propulsion Motors", Ser. No. 877,473, filed June 23, 1986 and invented by me with Takashi Koike and assigned to the assignee of this application, there is disclosed an improved semi-automatic system wherein the operator may selectively cause the outboard drive to be tilted to a desired position merely by selecting an appropriate directional switch and operating a main activating switch. Although that arrangement has the advantages which overcome the disadvantages of the previously proposed manual and automatic systems, it still requires the operator to make two selective settings in order to adjust the trim condition in at least one direction.
It is, therefore, a principal object of this invention to provide an improved device for setting the trim angle of an outboard drive in a semi-automatic manner and in which the operator need not make a number of control settings.
It is a further object of this invention to provide a device for setting the trim angle of an outboard drive that is simple in operation and which does not require great attention from the operator.
It is a still further object of this invention to provide a trim angle control device for a marine propulsion unit that is semi-automatic in operation so that the operator may select a preset trim condition which will automatically be effected when the watercraft reaches a certain speed.